/*
 * Copyright 2017-2022 original authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package io.micronaut.expressions.parser.ast.access;

import io.micronaut.core.annotation.Internal;
import org.jspecify.annotations.NonNull;
import io.micronaut.core.expressions.ExpressionEvaluationContext;
import io.micronaut.core.reflect.ReflectionUtils;
import io.micronaut.expressions.parser.ast.ExpressionNode;
import io.micronaut.expressions.parser.compilation.ExpressionCompilationContext;
import io.micronaut.expressions.parser.compilation.ExpressionVisitorContext;
import io.micronaut.expressions.parser.exception.ExpressionCompilationException;
import io.micronaut.inject.ast.ClassElement;
import io.micronaut.inject.ast.ParameterElement;
import io.micronaut.sourcegen.model.ExpressionDef;
import io.micronaut.sourcegen.model.TypeDef;

/**
 * Expression AST node used for context method parameter access.
 *
 * @author Sergey Gavrilov
 * @since 4.0.0
 */
@Internal
final class ContextMethodParameterAccess extends ExpressionNode {

    private static final java.lang.reflect.Method GET_ARGUMENT_METHOD =
        ReflectionUtils.getRequiredMethod(ExpressionEvaluationContext.class, "getArgument", int.class);

    private final ParameterElement parameterElement;

    private Integer parameterIndex;

    public ContextMethodParameterAccess(ParameterElement parameterElement) {
        this.parameterElement = parameterElement;
    }

    @Override
    protected ExpressionDef generateExpression(ExpressionCompilationContext ctx) {
        return ctx.expressionEvaluationContextVar().
            invoke(GET_ARGUMENT_METHOD, ExpressionDef.constant(parameterIndex))
            .cast(TypeDef.erasure(parameterElement.getType()));
    }

    @Override
    protected ClassElement doResolveClassElement(ExpressionVisitorContext ctx) {
        String parameterName = parameterElement.getName();
        ParameterElement[] methodParameters = parameterElement.getMethodElement().getParameters();

        Integer paramIndex = null;
        for (int i = 0; i < methodParameters.length; i++) {
            ParameterElement methodParameter = methodParameters[i];
            if (methodParameter.getName().equals(parameterName)) {
                paramIndex = i;
                break;
            }
        }

        if (paramIndex == null) {
            throw new ExpressionCompilationException(
                "Can not find parameter with name [" + parameterName + "] in method parameters");
        }

        this.parameterIndex = paramIndex;
        return parameterElement.getGenericType();
    }

    @Override
    protected TypeDef doResolveType(@NonNull ExpressionVisitorContext ctx) {
        doResolveClassElement(ctx);
        return TypeDef.erasure(parameterElement.getType());
    }
}
